The employment of microelectrophysiological techniques at the cellular level with multiple electrodes impaled in the functionally different tissues of the heart may be singularly advantageous in the study of cardiac dysrhythmias encountered so commonly in the course of acute myocardial infarctions: and, particularly in smokers with infarcted hearts. Investigation(s) shall also be instituted in isolated tissue to study the pathogenicity and treatment of cardiac dysrhythmia(s) and how the later is affected by smoking. The effect of selected coronary artery ligation, deprivation of oxygen to the tissues, and nicotine intoxication shall be assessed. In this manner, the role and site of conduction disturbances, as well as ectopic impulse formation, can be evaluated. Furthermore, the appropriateness and efficacy of a wide variety of therapeutic agents can be similarly assessed.